Hot Again Friday, Storms Likely This Weekend

It was a hot day across the area Thursday as temperatures jumped 10-20 degrees through out the Upper Midwest.  Even though it was awfully warm, it wasn’t uncomfortably hot for a lot of us.  That’s because our humidity levels stayed very low through the day as the added moisture just never made it to our region.  A southwesterly tilt to the wind is just one of the reasons why the dew points just could not climb.  Remember that our moisture comes from the Gulf of Mexico, which is to our southeast. So if there is a south-southwest wind versus a south-southeast wind, then moisture levels probably wont climb nearly as much because the origin of our air would then come from somewhere in the western Plains or Desert Southwest versus the Southeast or the Gulf of Mexico, both carry far more humidity.  Check out our afternoon dew points from Thursday.

It’s very easy to see for yourself that dry air was still in place.  If dew points had been in the 50’s, which is what we were expecting, then high temperatures would have likely been a few degrees cooler.  Why you ask?  Well, remember that it takes far more energy to increase the temperature of water versus the temperature of air.  Humidity or moisture is just water in its gaseous state that floats around with all of the other particles in our atmosphere.  The more water you have in the air, the harder it is for the temperatures to climb and for that matter, to fall as well.  This is why you typically see highs in the 90’s in the summer in places like Mississippi and Alabama, and 110’s in the summer in Arizona; it all has to do with moisture content in the air.

Now it looks like Friday will be another hot one with temperatures returning to the low 90’s in many locations, but humidity will be on the rise.  So if it rises faster then what is currently anticipated, afternoon temperatures may come up a little short.  But it won’t feel any cooler because the moisture will add humidity, which will make it feel just as hot.

But relief is in sight with a cold front expected to move through the area as we head into Saturday and Saturday night.  This will bring more widespread rainfall back to the area with the potential for some locally heavy rain.  Here is the current 3-day rainfall forecast from the Hydrological Prediction Center.

This shows that our area could have some decent rainfall this upcoming weekend.  Granted, some areas don’t really need the rain.  However, after the dry and warm week we have had, many locations could use a good soaker.  After all, May is typically our wettest month of the year.  Stay cool!